The phrase "a key transit point" is correct and usable in written English.
It can be used to describe a location that is crucial for transportation or movement, often in the context of logistics or travel.
Example: "The city serves as a key transit point for goods moving between the two countries."
Alternatives: "a vital transportation hub" or "an essential transfer location".
In the same cable, Mrs. Clinton described Qatar as the "worst in the region" on counterterrorism and Kuwait as a "key transit point" for terrorist money.
In common with its neighbours Kuwait is described as a "source of funds and a key transit point" for al-Qaida and other militant groups.
As a positive example, it noted that the "watchlist" in Turkey — a key transit point to Syria and Iraq — now included 12,500 individuals.
The dispatch and others offered similarly grim views about the United Arab Emirates ("a strategic gap" that terrorists can exploit), Qatar ("the worst in the region" on counterterrorism) and Kuwait ("a key transit point").
Proxy forces "have now surrounded Manbij city, which is one of the last junctions connecting Raqqa to the outside world and a key transit point for external plotters threatening our homelands", Carter said at the Washington meeting.
The links were supported by the British Council and welcomed by the Foreign Office in the years after the 9/11 attacks as the UK tried to bolster relations with a strategically critical central Asian state that had formerly been a part of the Soviet Union, and which is a key transit point in Nato's supply lines to Afghanistan.
In 2005, some 7,568 kilotons shipped through the O'Brien Lock, in the Cal-Sag Channel on the far South Side, which is the key transit point for cargo traffic between the lake and the Illinois waterway system.
The backbone is made up of high-speed cables that link big ISPs and key transit points on the net.
It was also a key transit station on the trade routes from Rumelia (Ottoman possessions in the Balkans) to Anatolia.
Moscow wanted the base, a key transit hub for the United States' war in Afghanistan, shut down; Kyrgyzstan wanted more money.
The politically unstable southeast or Balkans, is a key transit route for drug trafficking and illegal immigrants.
