President Donald Trump's decision to withdraw the vast majority of the roughly 1,000 troops in Syria left a bipartisan group of lawmakers flabbergasted in what they described as an abrupt foreign policy blunder.The US's adversaries, led by Russia, appear to be filling the vacuum and poised to exert influence over Syria.Russia's relationship with Syria continues to blossom as Syrian troops head towards areas occupied by the Kurds. Meanwhile, the Kremlin has been publicly sympathetic toward Turkey's campaign against the Kurds.The border conflict provides the Kremlin the opportunity to play the role as a mediator at the cost of US influence.Visit Business Insider's homepage for more stories.President Donald Trump's decision to withdraw the vast majority of the roughly 1,000 troops in Syria left a bipartisan group of lawmakers flabbergasted in what they described as an abrupt foreign policy blunder.As the issue sucked the oxygen out of Capitol Hill this week, the US's adversaries, led by Russia, appear to be filling the vacuum and poised to exert influence over Syria. Despite ideological differences between Syria and Turkey, the Turkish incursion provides the Kremlin the opportunity to play the role as the region's top powerbroker, which unlike the US, has forces on the ground.As the fate of the US's Kurdish allies dims with the US leaving, Russian President Vladimir Putin and his allies are pleased. Syrian President Bashar al-Assad, a strongman long opposed by Washington, is retaking part of his country his regime lost in the brutal civil war that began in 2011. Iran, another Russian ally, also looks set to expand its regional influence in what will likely be a setback for Saudi Arabia, the US ally that is its top competitor.An army of noneThe Kurds, a majority-Muslim ethnic group with no official state, consist of 25-30 million people spanning the Middle East. Despite their large population, they have been systematically oppressed and displaced as regional wars raged for decades. The trend continues in the current Turkish invasion of Syria, only this time, they are without US-backing and are targeted by all the parties involved.Kurdish forces and civilians were heavily relied upon by US forces in its campaign against ISIS. The US military presence in Syria was an unpopular domestic policy, and the Kurds, who waged war against the Islamic State, presented itself as the opportune proxy for an anti-ISIS campaign. The US-Kurdish relationship was integral in the fightthe Syrian Democratic Forces, a Kurdish-majority militia backed by US military assets, successfully ousted ISIS militants from their bastions and imprisoned them in makeshift detention centers.With US forces withdrawing from northeastern Syria, the Kurds in the region are left alone without assistance to face Syrian troops trying to reclaim the country's territory, and a Turkish-backed militia that views these fighters as terrorists.On Thursday, eight days after Turkey's forces launched an offensive into Syria, they agreed to a halt in operations, apparently on the condition that Kurdish forces depart an area on the border that Turkey is trying to seize by force. Trump, in announcing the agreement, called the area a "safe zone"in an echo of Turkish talking points.Read more: Turkey's president pulled one over on Trumpand some of the US's most dangerous adversaries are the big winnersThe Russian connectionRussia's alliance with Syrian leader Bashar Assad became ironclad as the Syrian government struggled to retain control during its civil warthe Kremlin used the conflict to test its military systems, like the Su-57 stealth fighter, and conducted airstrikes against civilian targets in rebel-held territories on Syria's behalf.The relationship continues to blossom as Syrian troops head towards areas occupied by the Kurds. Russian private military contractors are believed to be embedded in a Syrian convoy headed toward Manbij, Syria, a major city once held by ISIS, according to The Washington Post.Video footage taken by a pro-Russian news network also revealed scenes from a US base in Manbij, and a state-operated RT correspondent from its Arabic channel also reported inside the US base on Tuesday.But Russia's friendly tone does not end in Syriathe Kremlin has been publicly sympathetic toward Turkey's campaign against the Kurds. Russian officials have previously aligned themselves with Turkey's concerns over the alleged Kurdish threat. In a statement on Thursday, the Russian Ministry of Foreign Affairs said it was "seriously alarmed over the armed clashes in the border area," but added it did "not question the need to fight terrorists and to protect the security of Turkey."Read more: Trump is parroting Vladimir Putin's talking points as he defends pulling US troops from SyriaTurkey, which recently made a $2.5 billion missile defense purchase from Russia despite US protests, appeared receptive to Russia's stance on the conflict. Turkish President Recep Tayyip Erdo'an on Monday described Russian President Vladimir Putin's views as a "positive approach."On Wednesday evening, Russia reportedly announced Erdo'an had accepted an October 22 invitation to meet Putin in a resort at Sochi to discuss the military campaign."Putin likely can't believe his luck," a Western military official from the anti-ISIS coalition who served in Syria said to correspondent Mitch Prothero in a Business Insider report. "A third of Syria was more or less free of ISIS, and its security was good without any involvement of the regime or Russia, and now because of the Turkish invasion and American pullout, this area is wide open to return to government control.""What was supposed to be a diplomatically complex issue that would have involved US and European military power suddenly got as simple as sending in tanks and units unopposed throughout the eastern third of Syria," the official added.Waning influenceUS officials admit that the country's capabilities in Syria will be sharply limited by the withdrawal. Although a small, undisclosed contingent of US troops are expected to be stationed near Syria's border with Jordan, the lion's share of US forces in Syria are expected to redeploy elsewhere in the region."Look, we don't have a large footprint in Syria, so we can't be everywhere and know everything," one senior administration official said on Monday.US special operations forces deployed to Syria made an rapid exit this weekso quick that on Wednesday, the military launched two F-15E fighter jets to strike at its own ammunition-storage facility to "reduce the facility's military usefulness" and deny access to its supplies. Turkish-backed forces drew closer to the facility on Tuesday, according to The Wall Street Journal, and Kurdish forces who were training with the US there also set fire to portions of the base before their retreat.Read more: 'It's utterly pathetic': Democratic lawmakers are flabbergasted by Trump's 'tough guy' letter to TurkeyFears of an ISIS resurgence due to the Kurds's focus on the Turkish assault were also expressed by military officials. Roughly 10,000 people suspected of being ISIS members are detained in 20 facilities, some of which were attacked by Turkish forces, according to unverified reports from the SDF.The US appeared to confirm some of the accounts of ISIS prisoners escaping. In a statement on Monday, Defense Secretary Mark Esper condemned Turkey's "impulsive" actions and said the anti-ISIS efforts were compromised."This unacceptable incursion has also undermined the successful multinational 'Defeat ISIS' mission in Syria, and resulted in the release of many dangerous ISIS detainees," Esper said.US officials reportedly admitted it could not keep count of the potential escapees due to the withdrawal: "Nobody does," a senior official said to Defense One."The detainee issue is challenged by our force-posture changes," a defense official reportedly said on Tuesday. "We just have less eyes on the ground to know for sure what is happening."SEE ALSO:Turkey's president pulled one over on Trump ' and some of the US's most dangerous adversaries are the big winnersJoin the conversation about this storyNOW WATCH: Here's what 'Narcos' and 'Sicario' get wrong about Mexican drug cartels Click here to read full news..