Turkish army vehicles wait to pick up commandos returning from northern Iraq at the Turkey-Iraq border. Turkey's military said Friday it has ended a ground offensive against Kurdish rebels in Iraq, but said that foreign influence did not play a role in its decision. At least 200 trucks carrying Turkish troops were seen leaving the border area and heading into Turkey's interior.

Istanbul, Turkey ? Truckloads of weary and unshaven Turkish troops returned Friday from Iraq as Turkey ended an eight-day cross-border offensive against Kurdish rebels, meeting U.S. demands for a quick campaign.

Washington and Baghdad welcomed the move, but Turkey warned that the forces would return if necessary.

A key test of the effectiveness of Turkey’s ground incursion could come in the weeks ahead with the arrival of spring, the traditional start of the fighting season of the rebel Kurdistan Workers’ Party, or PKK. In the past, guerrillas have taken advantage of the melting snows and infiltrated Turkey from bases in Iraq, and any surge in PKK attacks could trigger another tough response from the Turkish military.

“It is very clear that an established group like the PKK will not be eliminated with one or two more cross-border operations. Turkey needs pinpoint operations against the group’s leadership, like Israel’s operations against Palestinian groups,” said Sinan Ogan, head of the Turkish Center for International Relations and Strategic Analysis in Ankara.

Moreover, the discrimination and poverty that triggered the Kurdish insurgency in Turkey in 1984 persist, although the government has taken steps in recent years to ease restrictions on Kurds as part of its bid to join the European Union. The PKK’s power has dwindled since its 1990s heyday, and Europe and the United States consider it a terrorist group, but it still enjoys support in the country’s predominantly Kurdish southeast and some urban centers.

The PKK has tempered its demands over the years, initially calling for an independent state and later for autonomy in the southeast and cultural rights. The conflict has killed up to 40,000 people.

Turkey’s first major incursion into Iraq for about a decade reflected the sensitive nature of its alliance with the United States, which provided intelligence to the Turkish military but sought a short campaign to preserve the relative calm of the mostly Kurdish region of northern Iraq. The troop withdrawal came a day after President Bush and Defense Secretary Robert Gates told Turkish leaders they should end the offensive as soon as possible.

“Any influence, either foreign or domestic, on this decision by the Turkish Armed Forces is out of the question,” the Turkish military said. “Terrorist activities in Iraq’s north will be observed in the future and no threat against Turkey from this region will be allowed.”

Gen. Yasar Buyukanit, the military chief, said it was “pure coincidence” that the withdrawal was announced one day after Gates issued his appeal during a visit to Ankara, Dogan news agency reported.

“This decision was made because the operation had reached its targets,” Buyukanit said. “When the U.S. defense secretary stepped into Turkey, the withdrawal had been partly realized.”

CNN-Turk television quoted Prime Minister Recep Tayyip Erdogan as saying: “Everything has been realized according to the plan. No civilian has been harmed in the operation.”