The US National Security Agency now has the legal right to monitor some 38% of the world's telephone, data and internet traffic without requiring a judicial warrant.
George W Bush signed the relevant legislation last Sunday.
According to Telegeography, a research firm that monitors telecommunications traffic flows, some 38% of the world's total telecommunications traffic starts or finishes in the US. This is down slightly from 43% in 2003.
"In 2005 (the latest year for which we currently have voice traffic data), approximately 29% of non-US voice traffic transited through a US hub. This is up noticeably from the 20% share in 2002," said Tim Stronge, a Telegeography spokesman.
"This only includes traditional, circuit-switched international voice traffic. If one includes voice traffic carried as Voice-over-IP (VoIP), the number would likely be around 33%," he added.
Stronge said his firm does not collect data on satellite traffic, but said no more than 1% or 2% of telecoms traffic went over satellite links.
"Fibre-optic network infrastructure is, bit-for-bit, far cheaper than satellites, and is the dominant medium for international telecommunications," he said.
"Taking into account that not all satellite constellations are US-owned, my guess is that less than 1% of the world's international traffic transits over US-owned satellites."