"We expect Turkey to abide by all of its commitments, and we continue to monitor the situation closely", Trump said.
Kurdish-led Syrian Democratic Forces (SDF), however, said that Turkish planes have dropped bombs on civilian areas, reported BBC.
Earlier in the day, Trump noted on Twitter that US forces "should never have been there in the first place".
Earlier Wednesday, Trump had taken angrily to Twitter, also to push back on criticism. A spokesman for Erdogan, Fahrettin Altun, writing in The Washington Post on Wednesday, called for global support for Turkey's offensive.
Daesh is an Arabic acronym for the Islamic State, or ISIS.
Trump has come under withering criticism in Washington, including from senior members of his own Republican Party, over what they see as a betrayal of the Kurdish militias that fought alongside USA forces to defeat the ISIS movement in Syria. "Yesterday, we saw USA troops, but this time they were on their way out of the area, and that terrified people", he said. The Turks were not entering Syria to fight the Islamic State, Graham said on Fox & Friends on Wednesday morning. The next time we ask the Palestinians to make concessions to achieve a peace plan, they will rightfully point to the Kurds as a reason not to trust us. "When it becomes apparent to them that they can not deal with this very modernized army and capabilities that Turkey has, then I think they will leave the area". I don't think so.
Sen. Susan Collins, R-Maine, on Wednesday reiterated that she considers Trump's decision to "abandon the Kurds, our major ally" in the fight against the Islamic State to be "terribly unwise".
But Syria said it was determined to confront any Turkish aggression by all legitimate means.
Trump's words are at odds with longstanding US policy of keeping thousands of American troops in the strategically important region, and his decision is being condemned by some of his staunchest Republican allies.
The Kurdish authorities in northeastern Syria called up civilians on Wednesday in readiness for the planned assault.
Kurdish forces who helped defeat IS fighters in the war-torn country have described the USA pullout from northeastern Syria as a "stab in the back". "This decision aids America's adversaries, Russia, Iran, and Turkey, and paves the way for a resurgence of ISIS". He said the US went to war under a "false & now disproven premise, WEAPONS OF MASS DESTRUCTION".
The Turkish lira weakened sharply against its major rivals on these remarks and the USD/TRY pair was last seen trading at 5.8002, adding 1.86% on a daily basis.
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.
North Atlantic Treaty Organisation appeared to give tacit approval to Turkey, a member state, to invade northeast Syria, while many European countries expressed concern.
'We ask the global community and all countries in the worldwide coalition against Daesh, who we fought together against and won, to carry out their responsibilities and prevent an imminent humanitarian disaster, the SDF said in a statement. In signaling the intent to invade, Erdogan appeared to buck threats of "economic obliteration" made by President Donald Trump on Monday, including possible sanctions.
Kurdish forces have dug trenches and tunnels in both areas, covering streets with metal canopies to block the cameras of Turkish drones.
"Turkey has no ambition in northeastern Syria except to neutralise a long-standing threat against Turkish citizens and to liberate the local population from the yoke of armed thugs", Altun wrote.
Trump announced the pullback of USA forces from their positions in northern Syria on Sunday, but threatened Turkey a day later with economic collapse should Ankara act, in ant way he deems "off limits" in Syria. With Turkey turning away from that agreement, however, the US troops at the center may be called on to instead monitor the Turkish operation and make sure that USA troops stay out of harm's way, the USA officials said.
Akcakale had previously been the site of a joint operations center for US and Turkish troops in coordinating joint air and ground patrols in northeastern Syria, an effort to ease Turkish concerns about the presence of the SDF.
