Egypt received 10 Apache helicopters from the United States in the past week, state media said on Sunday, a sign of improving frozen ties between the long-time allies.

"The move will open window for gradual easing the tensions between Egypt and the United States, who both have common fears over terrorism threats in the Middle East region," said Ahmed Mahran, political professor at Cairo University.

The delivery of Apaches was also announced Sunday at the website of the U.S. embassy in Cairo, after the United States announced in April that it had decided to unfreeze military deals with the North African nation for "counterterrorism" efforts in the Sinai Peninsula.

The U.S. annually allocates some 1.5 billion U.S. dollars in aid to Egypt, including 1.3 billion dollars in military assistance.

The aids were frozen in October, 2013 after the military ouster of the country's first elected president Mohamed Morsi and subsequent crackdown on his supporters.

The United States, which led a coalition for fighting the Islamic States (IS) in Iraq and Syria, is concerned over the critical developments and divisions in the region that might lead to devastating war that would harm its interests in the Middle East, Mahran told Xinhua.

"Egypt for the west is a milestone for stability in the region," he added, given the fact that the most populous Arab country has been engulfed in militant insurgency which took from lawless Sinai a stronghold for attacking security forces.

The United States has blacklisted the most powerful militant group in Egypt, al-Qaida inspired Sinai-based Ansar Bayet al-Maqdis, which pledged allegiance to the IS and announced "Sinai State" in April.

On Thursday, U.S. Department of State designated another Egyptian militant group, Ajnad Masr "Soldiers of Egypt", as a terrorist group.

"This is recognition of U.S. that Egypt faces terrorist threats, not only over its borders with Israel and Libya but domestically," said Megahed Zayat, expert with Egypt-based National Center for Middle East Studies.

Designating the two extremist militant groups as terrorist by U.S. means United States back for Egypt's efforts in combating terrorism, Zayat told Xinhua.

According to Yousry el-Azabawi, an expert with Ahram Center for Political and Strategic Studies, "Egypt is a significant player in the international efforts in the war against the IS and the expansion of extremism in the region."

Logically, the ties between the two countries should signal improvement to face the terrorist groups, the IS in particular, Azabawi added.

By finishing its constitution and presidential elections, and with the parliamentary elections at doors, Egypt has made progress in the road map announced after the ouster of the Islamist leader Morsi, he added.

Azabawi expected "gradual and slow improvement in the two countries ties during the left two years in U.S. president Barak Obama's reign," arguing the relations needs years to restore the same strength it has during the time of Egyptian ousted president Hosni Mubarak, who was the U.S. main ally in the region and the basic guarantee for Israel security.

"Combating terrorism and economic development are two basic pillars to head towards the right track of relations," he added.

U.S. direct foreign investments came first in Egypt with 19.6 billion dollars in 2013, which is third of the total U.S. investments in Africa.

Another sign of rapprochement between the two countries was seen as the U.S. returned an ambassador to Cairo on Thursday, with Stephen Beecroft assuming his office, after 16-months absence of diplomat in the top job at the U.S. embassy in Cairo.

The post was previously held by Anne Patterson who left shortly after the ouster of Morsi.

On the same day as Beecroft's arrival, Sisi and U.S. president Obama discussed in a telephone conversation means of enhancing bilateral relations, and boosting cooperation in counterterrorism and regional security efforts including military and intelligence relations. Endit