Iran has warned Turkey several times to respect Syria's territories and urged all foreign military forces "with an illegal presence", including the United States, to leave Syria. "They may wake up and wreak havoc in the country".
Graham had warned Turkey on Tuesday of "sanctions from hell", if it moved forward with the attack.
"A Turkish military advance into Syria threatens to halt momentum against ISIS, directly assaults our SDF partners, and could give the likes of al-Qaida and Iran new footholds in the region", Rep. Kevin McCarthy, R-Calif., tweeted. The U.S. military has been backing the Kurds in the fight against the extremist group the Islamic State (or ISIS). Trump's critics and many analysts believe that Turkey will target the Kurds when the USA withdraws. Turkey regards the YPG as indistinguishable from the militant Kurdistan Workers' Party (PKK), which both Ankara and Washington consider a terrorist organization.
In 2016, Operation Euphrates Shield was launched with the intent of targeting IS in northern Syria and then Operation Olive Branch in 2018 saw the YPG driven out of the northwestern region of Afrin.
"Turkey has no ambition in northeastern Syria except to neutralize a long-standing threat against Turkish citizens and to liberate the local population from the yoke of armed thugs", he said. Economic or political pressure may have pushed Ankara to agree to the quid pro-quo, he added, but it's a deal "I would not have accepted".
Following a four-year campaign, SDF fighters, backed by USA air support and artillery, took out the last ISIS stronghold in southeast Syria near the Iraqi border in May. That demonstrates "a complete lack of understanding of anything happening on the ground", former USA special envoy to the global coalition to defeat ISIS Brett McGurk wrote on Twitter.
Now, with Trump's retreat from Northern Syria, he is choosing to have the back of Turkish President Recep Erdoğan, a known Putin protege, rather than the Kurdish fighters who have fought alongside American troops against ISIS and other terrorists for decades. The group's leaders told the Times that there have been no discussions with USA officials about turning over the camps to Turkey. It also would ignite new fighting in Syria's 8-year-old war, potentially displacing hundreds of thousands.
Iranian President Hassan Rouhani, a close ally of Syrian President Bashar-Al-Assad, told state media that the "presence of the Syrian army" is the "only solution to ensure safety and security in southern Turkey and northern Syria".
In order to counter the rising xenophobia, Erdogan has promised to relocate two million Syrians in areas captured from the YPG, even if they do not originate from there. "One is to release them... or to kill them".
Turkey has been massing troops for days along its border with Syria and vowed it would go ahead with the military operation and not bow to the US threat.
The Kurds guard thousands of IS fighters and their relatives in prisons and camps in areas under their control and it is unclear whether they will continue to be safely detained.
The unprecedented nature of Turkey's attack on Wednesday, bombing peaceful towns along the border with impunity, represents not only a setback for 30 years of U.S. policies in the Middle East and around the world, but also a change in the concept of worldwide law and the change in the way Western powers deal with partners that used to fight ISIS.
Ankara's goals may end up being more limited than that, says former foreign minister Yakış.
Stoltenberg will discuss the military action with Erdogan on Friday in Istanbul.